Beam type electron discharge device



Dec. 30, 1952 B, C, GARDNER 2,624,021

BEAM TYPE ELECTRON DISCHARGE DEVICE Filed April 18, 195o Patented Dec.30, :1952

UNITED STATES PATENT OFFICE.`

BEAM TYPE ELECTRON DISCHARGE DEVICE Bernard C. Gardner, Redwood City,Calif., as-

signor to Raytheon Manufacturing Company, Newton, Mass., a corporationof Delaware Application April 18, 1950, Serial No. 156,660

(Cl. S13-72) 9Claims.

This invention relates to electron discharge devices, and moreparticularly to an amplifier of the deflection modulation type which maybe used as an analogue computer. y f

Cathode ray tubes can be used as analogue computers by placing a targetin the path of the electron stream and masking said target with theshield having a particular configuration such that the beam impingespartially on the mask and partially on the target electrode. By thendeflecting the beam, the number of electrons striking the targetelectrode may be varied in accordance with any desiredV function of theinput deflection voltage by the use of a particular contour'of maskingelectrode. For example, a beam may be emitted from a cathode ray tubegun in the form of a triangular plane with the apex of the plane at thegun' and the base of the plane a vertical line of impingement ofelectrons on the target or masking electrodes. If the electron beam isthen moved horizontally such that the position of the line ofimpingement of the beam on the masking electrode changes, the contour ofthe edge of the masking electrode will determine the number of electronsstriking the target electrode.

It has been found that certain inaccuracies are inherent in this devicesince the ends of the line of impingement of the beam would not have adensity which is uniform with respect to the density of the impingementline at the y center thereof. Therefore, it becomes impossible tocompute exactly the shape of the curve vof the masking electrode. Sincethe accuracy 55.-,

of the device depends upon the accuracy to which the curve of themasking electrode is computed, and, since adjustment of this curve isimpossible following assembly of the device, it has been found to beimpossible to construct this l type of computer with large degrees ofaccuracy.

This invention discloses a beam deflection device wherein the edgeeffects of the beam are eliminated, and hence the curve of the maskingelectrode may be computed with a high degree of accuracy.

Briefly, the invention embodies the use of an electron beam in the formof a disk, the electrons of said beam emanating from a cathode at thecenter of said disk. The periphery of said disk impinges upon anapertured, cylindrical masking electrode behind which is positioned atarget or collecting electrode. Disk-shaped deflection plates arepositioned substantially parallel to the electron beam disk such thatthe voltages applied between the deflection plates cause the disk to bedeformed into a conical beam so that either more or less electronsimpinge upon the masking electrode, the number of electrons impingingupon the masking electrode being controlled by the size and shape ofapertures therein.

In addition, since the total current of the bean is limited by the areaof impingement of the electrons on the anode structure and the resultantheating thereof, the radial or disk type beam allows a much highercurrent than a linear type beam with the resultant higher signal level.Also, the radial type device disclosed herein may be made considerablymore compact than a linear type device, being, for example, two or threeinches in diameter and two or three inches in length as against asimilar diameter and ten Eo twelve inches in length for a linear typestrucure.

Other and further advantages of this invention will become more apparentas the descrip- .tion thereof progresses, reference being had to theaccompanying drawing, wherein:

Fig. 1 illustrates a longitudinal, cross-sectional view of an electrondischarge device embodying this invention taken along line I-I of Fig.2;

Fig. 2 illustrates a transverse, cross-sectional vview of the deviceshown in Fig. 1 taken along line 2-2 of Fig. 1; and

Fig. 3 illustrates a circuit utilizing the device of Figs. 1 and 2.Referring now to Figs. 1 and 2, thereis shown ran evacuated envelope I0which may be made,

for example, of glass having positioned therein -a cathode II coaxialwithy envelope Ill. Cathode II comprises a cathode cylinder I2 which maybe of any' desired conductive material such as, for example, tungsten.Inside cylinder I2 is a heating element comprising a coil I3, one end ofwhich is attached to the cylinder I2 and the other end of which extendsdown through the bottom end of cylinder I2 and is connected to a lead-inmember Id which. passes through a glass seal in the base of envelope I0.The cathcae cylinder I2 is supported by a similar leadin member I5 whichpasses through a glass seal inthe base of envelope II). :A portion ofthe outer surface of cylinder I2 is coated with electron emissivematerial Il such that, when a suitable heater voltage is applied betweenleads .I4 and I5, cylinder I2 will be raised to a sufficient temperaturefor coating I1 to emit electrons.

Surrounding the portion of cylinder I2 which 1s coated with electronemiss'ive material and coaxial therewith is a masking electrode I3 whichis cylindrical in form and has a plurality of apertures therein. Maskingelectrode Ill is supported by a plurality of lead-in members IS whichpass through the bottom of envelope I and are sealed therein.Surrounding masking electrode I8 and coaxial therewith is a collectingelectrode 23 Which is cylindrical in form and is supported by aplurality of lead-in members 2v! which are sealed through the bottom ofenvelope IQ.

Positioned above cathode II is a metallic disk 22 which is supported bya lead-in member 23 sealed through the top of envelope Ill. Disk 22operates as a deflection plate and is positioned slightly above theupper end of masking Aelectrode I8 and is somewhat smaller in diameterthan masking electrode I8. Positioned below masking electrode I3 is asecond deflection plate 24 which comprises a liat, annular metallicmember supported by lead-in members 25 sealed through Ythe bottom ofenvelope Ill. Member 24 has an outside diameter which is equal to thediameter of member '22 and has a hole 2B in the center thereof to allow4the passage of the cathode I I therethrough.

Referring now to Fig. 3, there is illustrated a mode of operation of thedevice of Figs. 1 and 2. The heater coil I3 has a voltage appliedthereacross by means of a battery 21. Cathode II is attached to avariable tap 28 of a battery 29 which may have a total overall value of,for example, a few hundred volts. The negative end of battery 29 isconnected through input load resistors 3Q and 3l to lower and upperdeection plates 24 and 22, respectively. An input signal amplifier hasits output connected across electrodes 22 and 2li, whereby a signal .isimpressed therebetween. Masking electrode iii is connected to .a tap 32on battery 23 which is considerably more positive than variable tap 28.Collecting electrode 2t is connected through an output load resistor 33through the positive end of battery 29. rlhe electron beam is attractedto masking electrode I8 and collecting electrode 2l! due to the positivepotentials between the cathode I I and said electrodes. By adjustment ofvariable tap 28, the negative bias on the deflection electrodes 2li Vand22 may be adjusted such that the point of impingement of the electronbeam on 4the masking electrode I8 is a sharp, Ycircular line. Ifdesired, other electrodes may be used in the structure to facilitatefocusing 'and .to control the intensity of the electron beam.

When a voltage is applied between Yelectrodes 22 and 24 by a signal froma signal input arn- .plier 34, the beam will be moved either up or downat the point of impingement of said beam on masking electrode I 8dependent on vthe instantaneous polarity of the input signal. lDue .tothe non-uniform shape of the apertures in the masking electrode I8,movement of the point of impingement of said beam on masking electrodevI8 varies the current which passes through said apertures to thecollecting electrode 2B, thereby varying the voltage developed acrossload resistor 33. The voltage developed across resistor 33 is fed to anoutput signal amplifier to be used for any desired purpose. By varyingthe shape of the apertures in masking elect-rode I 8, .the output signaldeveloped across resistor 33 may be made to have any desired functionalrelationship to the input signal applied to plates 22 and 24. In effect,the output signal represents the solution of a particular problemaccording Cil 4 to a particular formula and, therefore, the system maybe termed an analogue computer.

If desired, the output electrode may be made in a plurality of sections,each section covering one or a plurality of apertures in the maskingelectrode I3. Each output section may be fed to a different output, andthe apertures in front of the various output sections may `havedifferent shapes, whereby a plurality of different functions may becomputed simultaneously. Due to the fact that the beam is radial, it hasno end points in .a direction perpendicular to the deiiecting direction,and hence the inaccuracies which are encountered in linear beams areeliminated.

This completes the description of the particular embodiment of theinvention illustrated herein. However, many modifications thereof willVbe apparent to persons skilled in the art. For example, the signalcould be taken from the masking electrode rather than the collectingelectrode, if desired. Other types of cathodes could be used, and anydesired shape or size of aperture could be used in the masking electrodeI8 Without departing from the spirit and scope of this invention.Therefore, applicant does not wish to be limited to the particular`details of the embodiment of the invention illustrated herein, exceptas defined by the'appended claims` What is claimed is:

1. An electron discharge device comprising an electron source, means forforming electrons from said source into a conical beam, a targetelectrode, and means for varying the conical angle of said beam prior toimpingement of said beam on said target electrode to thereby vary thenumber of electrons impinging on said target electrode, the percentagerof said beam which impinges on said target electrode varying as acontinuous function of said conical angle.

2. An electron discharge device comprising .an electron source, meansfor forming electrons from said source into a conical beam, Va maskingelectrode having non-linear discontinuities therein upon which a portionof said beam will impinge, a collecting electrode, and means for varyingthe conical angle of said beam prior to impingement of ysaid beam .onsaid masking electrode to thereby Vary .the number of relectronsIimpinging on :said Vmasking electrode.

.3. An electron discharge device comprising an electron source, meansfor forming electrons from said sourceinto a conical beam, a maskingelectrode rhavingan aperture therein, said aperture .having a non-linearcontour, a collecting electrode positioned outside said maskingyelectrode, and means for varying the conical angle of said beam priorto impingement of said beam on said masking electrode.

4. An electron discharge device comprising-an electron source, means forforming electrons from said source into a conical beam,a maskingelectrode upon which a portion of said beam will impinge comprising anapertured cylinder surrounding said source, a collecting electrodepositioned outside said masking electrode Acoaxial with said source, theapertures of said cylinder having sides which are non-linear in adirection parallel to the axis of said beam, and means for varying theconical angle of said beam prior to impingement of said beam on saidmasking electrode.

5. A computer comprising an electron discharge device Yhaving signalinput means and signal output means for producing a vsignal outputbearing a non-linear continuous functional relation to a signal suppliedto said input means, said discharge device comprising an electronsource, means for forming electrons from said source into a conicalbeam, a target electrode which is non-uniform with respect to said beam,and means prior to said impingement of said beam on said targetelectrode for varying the conical angle of said beam.

6. A computer` comprising an electron discharge device having signalinput means and signal output means for producing a signal outputbearing a non-linear continuous functional relation to a signal suppliedto said input means, said discharge device comprising an electronsource, means for forming electrons from said source into a conicalbeam, a masking electrode upon which a portion of said beam will impnge,a collecting electrode positioned outside said masking electrode, andmeans prior to the impingement of said beam on said masking electrodefor deflecting said beam substantially transversely to the direction ofmotion of said beam.

7. An electron discharge device comprising a source of electrons adaptedto produce a conical electron beam, an electrode positioned in the pathof said beam', said electrode having a discontinuity therein whichvaries as a continuous function of the conical angle of said beam, and

a beam deflection element intermediate said source and said electrode tovary the conical angle of said beam.

8. An electron discharge device comprising a source of electrons adaptedto produce a conical electron beam, an electrode positioned in the pathof said beam, said electrode having an aperture therein which varies asa continuous function of the conical angle of said beam, and a beamdeiiection element intermediate said source and said electrode adaptedto vary the conical angle of said beam.

9. An electron discharge device comprising a source of electrons adaptedto produce a conical electron beam, an electrode positioned in the pathof said beam, said electrode having a discontinuity therein which variesas a continuous function of the conical angle of said beam, a beamdeflection element intermediate said source and said electrode adaptedto vary the conical angle of said beam, and a target positioned in thepath of said beamk on the opposite side of said electrode from saidsource.

BERNARD C. GARDNER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,164,922 Hollmann July 4, 19392,176,589 Hollmann Oct. 17, 1939 2.205.500 Strutt et al. June 25. 1940

